"
Mammals and birds are traditionally thought to be the planet's only warm-blooded animals, keeping their body temperature consistently warmer than the outside environment.
Fish and reptiles are almost entirely cold-blooded, or "ectothermic"; they are at the mercy of the environment for their warmth and largely get by on slower metabolic rates."

While normally cold blooded, it heats up when near humans because It feeds on brain wave energy, absorbing all unconscious frequencies and then excreting telepathically a matrix formed from the conscious frequencies and nerve signals picked up from the speech centres of the brain, the practical upshot of which is that if you stick one in your ear, you can instantly understand anything said to you in any form of language: the speech you hear decodes the brain wave matrix.

While normally cold blooded, it heats up when near humans because It feeds on brain wave energy, absorbing all unconscious frequencies and then excreting telepathically a matrix formed from the conscious frequencies and nerve signals picked up from the speech centres of the brain, the practical upshot of which is that if you stick one in your ear, you can instantly understand anything said to you in any form of language: the speech you hear decodes the brain wave matrix.

"Their circulatory and respiratory systems are almost unique among fish (only mackerel sharks share this ability), enabling them to maintain a body temperature higher than that of the surrounding water. "